An important point to note is that profile requests will only resolve for the hash of the primary address on an account. Users may have multiple addresses on a single account, so while a Gravatar image request may return a result, a profile request for the same hash may not.

hCard

Profile pages are fully marked up using hCard, a microformat for programmatically embedding information about people, companies, organizations, and places in HTML and other markup languages. The screenshot below describes some of the main markup involved on a profile page

Email address marked up with class=email (only available via JS/client-side parsing due to spam-protection measures)

IM accounts marked up using class=url (some values only available via JS/client-side parsing due to spam-protection measures)